Traffic Operational Performance Evaluation and Enhancement of a Roundabout: A Case Study of Lakhan Thapa Chowk, Butwal
https://doi.org/10.46610/JoRAIS.2025.v010i01.004
Keywords:
Calibration, Delay, LOS, Operational speed, Queue length, ValidationAbstract
The study explores various alternatives to improve the operational performance of the Lakhan Thapa Chowk roundabout in Butwal, Nepal, focusing on key parameters such as Level of Service (LOS), delay, queue length, and average operational speed. Using a VISSIM microsimulation model, four improvement alternatives were evaluated: Alternative I (improved roundabout geometry), Alternative II (increased lane width and number of lanes at the Bardaghat leg), Alternative III (grade-separated intersection along Siddhartha Highway), and Alternative IV (grade-separated intersection at Siddhartha Highway with an at-grade roundabout). These alternatives were assessed for both the base-year and forecasted traffic scenarios, after 5-year and 10-year. The results revealed that Alternative IV is the most effective solution, achieving LOS B for the base year with a delay of 12.06 seconds, a queue length of 18.06 meters, and an operational speed of 37.19 km/h. Similarly, for forecasted years, i.e., after 5-year and 10-year, Alternative IV continued as the best alternative among others maintaining strong performance, achieving LOS C, 24.4 seconds delay, 36.95 meters queue length, 33.03 km/h speed in 5-year forecast and LOS E, 47.68 seconds delay, 37.72 meters queue length, 26.95 km/h speed, in 10-year forecast respectively. These findings demonstrate that Alternative IV, which integrates a grade-separated intersection with an at-grade roundabout, is the optimal solution for enhancing traffic operational performance under both current and future conditions.
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